Teaching system employing a television receiver

ABSTRACT

An electronic audio-visual teaching system employing essentially a cathode ray tube and associated electronic apparatus and a transparent manually operated spatial response signal generator which coacts with the cathode ray tube whereby feedback between students and teaching machine is readily achieved. Provides considerable ease in programming. Also can be used for remote polling of viewers.

United States Patent us] 3,671,668 Relflel 1 June 20, 1972 (s41 mcnmc SYSTEM mm 3399.401 411%: m.....mm..n...m.......amz4.I TELEVISION RECEIVER 3,413,515 "968 Ml......................... "17816.8 4 2,168,047 8/1939 smmm....m..,...... .......mm (121 In w hg -i we. 2 2.24|.s44 5/1941 Dnyu 1m: x m. 160610 3.423.528 1/1969 mm... m mm 1221 mumrunucxnons 7 I2 1 pv m ammaxmvcwdimlmm m4 TKlLWBIIMI-VOLLNO-6-AFKI9SQ-W.I3,

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. "816.8, I9; 3401324 A [57] ABSTRACT I'm-u all An electronic leaching system employing caen- [$6]. tillly a cathode ray tube and associated apps UNITED STATES PATENTS Ind l m P= W m "I" 1 generator which ooacts with the cathode ray tube whereby 3,126,646 Pm u "35,9 m m and wxhing whine i 3. 29. 4/1964 achieved. Provides comiderable cue in programming. Also 3.337.860 8/1967 can be medfonenm polling ofviewen. 3.382.588 5/!968 3.394.366 7/1968 SChJDr-whlhu [a -m n w 4 l3 2 mo in mam" convzmn II 4 w *3;

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sscrronouxnor'me men-non 'l'here arepreaently available anurnberof audio'visual teachingsystemsotvarying degreesofaophistication. These includesimplefilmstripprojectorswithorwithoutrelated audio whereby an student or class easen' 2 Yetmotherobjeetofmyiavsationistoprovidsa-aaa polling"viswershyatltrrslyaun'verlralrusansifrlssherl tomrprefereneeamongohjaetsorpersomdwplayad' torlallyonthel'vreceiverscreemtheirsslection rressadvhdireetcrmtaetofthepreferredobjeetb mnusllyoperatadprebealoeiatedwiththespat'nlraape rpalgenerasor.

'lhereandotherm aatursaaadadvantagasofmy ventionwillbecomeapparenttothoseskiledinthisparticr monomer-Momma companyingdrawingainwhich:

FlGJisahlockdiagramofmyoveralsystem; FlGJisaschematiediagramofaspatialreapcaseig y receivesalecturewithoutintermittentfeedbackfromthestu- 5 so greatly adds to the realism of the "live lecture" presentation. Such interplay appears to be important in the educational or information transfer process. Certain modifications have been made in the simpler systems which do permit a limited student feedback and pace control. For example, there are film strip programs with related audio having questions at spaced intervals and requiring the correct response principally by operationsofpush buttonsorthe like beforethefllm strip proceeds to the next Teaching machines ofthis nature are, of course, quite well known to those skilled in the art. Whiletheyhadbeenocceptedinactualpracticqtheystill present limitations in teacher-student reaction.

Also in present teaching machine art are those systems employing electronic digital computers as one, but very substantial, component thereof. With such devices there is ready in terplay-feedback-between student and computer but the equipment investment required is relatively great and the educational topic must be programmed into computer language. Between the cost of computers and the cost and diffaculty of programming, only a relative handful of these more generator herewith.Suchsignal FlGSJanddarewiringdiagramsforaaehrewih.

DESCRIPTION orrnernemurzn ennoonmrr lhepreferredemhodimentshereofwillbedeaenbedmcr 2o junctionwithsuchdrawingalwouldnotethatthisdeacripti willessentiallybeintwopartgthefirsttoconsiderther pammsfromtheviewen"standpoint,andtheseeond theatandardtelevisionreeeiverandwhichhasafaceplatel Poaitionedinfrontofaaidfaceplateiatheqaatialsiga ,geoerallynotedbythenurneral l3,whiehl|a gcaeratorislockedintopositioaintrol offaceplate l2asforesarnple,hyflangea Morthelih Thereisaslightairspace lsbetweenthefrontofthefar platel2andthebackofthegeneratorl3.

Apictureiadisplayedonthefaceplateottheteleviaiu receiverllintheknownmanner.8uchpictureandrelate audioinformatiomfremanaudioarnplifierandspeaker Ill present the basic instructional mater'nI-e.g., the lecture an questions relating thereto. A source of such instruction;

materialmaybeafilrnslidesyatemwithrelatedvide scanning Mm and magnetic tape voice recorde knowntothoaeskilledintheartandcommerciallyavailablea theSylvanisScannerColorSlide'lheater(abrochuredeserib ingwhich'uappendedhereto)orthesourcemaybevideotap sophisticatedsystems have rm theirway intotheclassroom.

lndistinction ofthcseteachingsysternaofthepriorart,l have invented a novel teaching or information transfer system which is relatively inexpensive, easy to use and manufacture andflesiblelorbothstudentandinsn-uctororintormation source.

in thepreaurtteachingsystemaaishereafterdeaeribedin greater detail, I employ the cathode ray tube and circuitry of a standard home television receiver for example as one componenttheredilpositioninfrontofthefaceplatcofsald receiver a manually operated spatial response signal generator which is actuatable by the student and which generates a signal coacting with other signals including the image produced on the video face plate. There must be, or preferably is, correct feedback by the student to continue with Preferably boththeatndent, whenviewingmndtheinnruetor when programming, should be able to stop the backgroear visualgeneratoratpartieularpointsinordertoeitheranswel orpreaentquestionsaudthequestionsarepreferablyan swered beforetheprogramcontinues. Thuswhileatandard retevisioncanireuaedwithmyinventiomcqsecially inthe"polling"modetobediacuasedlater,itiapreferahle,for purposegthattheseothermeansnfselfplate lzmayreadilybeaeenthroughsuchrignalgensratorp Anelectricallyconductingprobeliiasssociatedwiththe signalgeneratcr,functioostherewith,andisusedbyboththe the presentation and the student procwds at his own pace. mmudthemwpickdfmx'my'mwm' Thesamebasicequipmentisuaedforprogrammingasiused bytheatudent.

Accordingly,aprineipalobjectofmyinventionistopmida ateachingsystemwhereinreadyspatialresponaerelativetoa televisionimageisaceomplishedbythestudentorviewer.

Another object of my invention is to provide a teach system which employs a cathode ray tube background or iadisplay device and means coacting therewith wherebytheludentmayreadilyreapondtoandcoatrolthe vofthepl'ograrnbeirrgpreaented. i furtlrerobjectolruyinvelttiorristopruvidearraudio- 'risualteachingsystemasingnrb-videofrequencieaiaboththe programmingandcontrelofthepaceofpiaybackwhereh propercpatialresporuerelativetoavideoimqearerequired ottheviewer.

dinatea'gnaltherefrormllowallthiaisaecomplishedwilba subsequentlydeacrihed.

Before proceeding further with the description of my overallsystem,referenceshoulduesthehadtom.2to-

derstandthenanrreandconstrnctionofoneeashodbsatof lama.

Theprobelcoaetswiththe 'l'hecoaetioaolths probeaadphteisenployedtndetermineaedpicholthsX- 3 andY-positionofthepsobeatitapoiatdcontactwiththe plate. Many different means for this are available. For camaple,adiode switchingsystemorastylusattached hyrigidor string-like members to a pair of potentiometers may be used herewith. Furthermore, a digital position data generator in which the probepositieaisidentifiedbyuaeofapairofintsrinsulated, intersecting, open grid works of wires or other forms of conducting lines may be employed.

In the embodiment of such plate, as illustrated in FIG. I, a DC potential is impressed in the vertical direction across the glassplate llbyaDCgenerator IQthroughthe bankofinductors and It. At the same time an AC potential is impressed in the horizontal direction across the electrically-conducting transparent member II by an AC generator 23 through a bank of capacitors 24 and 25 which block any effect of the AC circuit on the coacting DC circuit and vice versa. It will be understood, of course, that the AC and DC actuation of the generator could be reversed. Furthennore, as noted above, a diode switching system can similarly be employed in lieu of the capacitors and inductors.

Proceeding with the description, the AC and DC signals are provided with a ground reference 27 by the tie-point contact 26. By thii means, an AC signal is superimposed upon the DC and the amplitudes of the signal at any point on plate 18 are proportional to the horizontal and vertical distances of the probe from, for example, the lower left-hand corner of such plate.

The probe 16 picks off a mixed signal from the plate II which signal contains electrical information for determining the exact point of contact between probe and plate-i.e., such signal provides the X and Y coordinates of probe The signal contains both an AC component giving the horizontal distance and a DC component giving the vertical distance from a reference point usually as noted above the lower left-hand comer of the plate. Such signal is then split into its AC and DC components which take part in the student answering or viewer-polling aspect of the invention, namely whereby the student answers questions posed on the face plate 12 or on the other hand as used by the instructor in programming the apparatus for subsequent instructional use.

The mixed signal picked off by probe 16 is conveyed via lead 28 (at this point reference should be had to both FIG. I and 2) to a number of electrical components of known construction which serve essentially to split the signal into the AC and DC components thereof for subsequent use. This is accomplished in the signal separator 29, representative details of which are presented in FIG. 2 along with other circuitry to be used in preparation of programs as will be discussed later.

Lead 28 from the probe 16 is split into leads 30 and 31 in the signal separator 29. the AC and DC components of the signal are split with lead 30carrying the AC and lead 31 carrying the DC component. In the AC signal carrying lead 30, there is provided a capacitor member 32 which blocks the DC component but permits the AC signal to proceed. Such AC signal is then passed through a rectifier 33 where it is converted to DC and from thence to a carrier modulator 34 operating in conjunction with a carrier oscillator 35. The carrier envelope stemming from the latter contains probe X-coordinate position information which is fed into amplifier 36 via lead 36a.

Similarly, DC signal in lead 31 is fed through an inductive choke 3la to produce a slowly varying DC and from thence mums:

gramming is accompl'mhed will be subsequently described thisspccifieationbutforpurposesctdiseusaionatthispoi letitbeaaidthatthemagnetierecmdergeneratesasigl represeatativeoftheproperx-coordinatesndasseondsigl 5 representativeoftheproperY-coordinateandthatinl eompasatorsflandflthesigaahfromtheamplifisrsfis dlarecomparedwiththesignalscomingfromthets recorder.

Fromthetwovoltagecomparatormembersflandflr reapectively.'lhesefeedintoanand"circ memberdwhichfeedsmtenabling"signaivialead47,ss intoleadsuanddfintotheirnagestcrageandvideoconw tor member 50 and the magnetic recorder 43. The ima 5 storage and convertor member 50 controls the operation thecathoderaytubescreenvialead 51.

For the moment, in considering this aspect of the inventic the lead! into the tape recorder should be disregarded.

Depending on the position ofthe probe 16 in contact wi 20 the plate ll, two voltagesare generated by the voltage gener tor, namely that of the X-component and the Y-component probe position which are compared with two voltage signs coming from the mpe recorder, comparison taking place the voltage comparator members 37 and 42. 1f the two vo;

25 ages are identical of substantially identical, the comparate operate to permit the and" circuit member 46 to be actuatl andthis,inturn,enablesthevideoandaudiopreaentation proceed lwouldnotethatwhenthesignalsfromtheprobelss gothesignalafromthemagneticrecordenwhichlidentifyz signalsX andY'arebeingcomparedin thecomparators! and 42 the magnetic recorder is essentially stopped-Le, tl tape is not moving. Because of this, the "proper" or X'-aign is stored as a charge on condemer it, subsequently only an plified by amplifier la and the "proper" or Y'-signal is store as a charge in a condenser 62 and subsequently amplified h amplifier 62a. The X'- and Y'-signals are placed on til storage condensers just before the tape recorder is shut dovn Their amplitudes are, of course, derived from suitable trael orcarriersplacedonthetapebytheprogrammer.

Note that the X and X-coordinate voltages and the Y- an Y'-coordinate voltages, if the same, or substantially the samr then trigger the comparators 37 and 42 to send two signals t the "and" circuit member. If the X- and X'-signals are not th same orsubstantially the same or the Y- and Y'-signala are no the same or substantially the same, the "and" circuit remain inoperative.

Atthispointinthelessonwhichisbeingviewcdbythestu dent, the image storage system and video scanning eonverto is usualiy presenting a series of signah producing a sta tionary picture on the screen 12 ofthe cathode ray tube I1. I: order that such member 50 signal the presentation of sub sequent pictures, it must receive the correct signal to do a from the and circuit member and the converter onl receivessuchsignalifthestudenthasappliedtheprobelitl therightplaceonthespatialgeneratorld.

Forpurpcaesofdiscuasiomassumethatthelemonha proceededtoacertainpointandnowaquestionisraisedil the pre-programming which question has four possible an swers and that such four possible answers are printed scroa thefaceofthecathoderayhibe.'lheseareindifferentspatia positionsobviously,andarenotedasanswersA,B,C,andD "lhestudentisaskedtoanswerthequestionbyapplyingthr into a second carrier modulator 38 operating in conjunction 5 probe to points A, B, C or D which identify the answer. For l with a second carrier oscillator 39. The carrier envelope stemming from this modulator and oscillator is fed via lead 39a into, for example, the amplifier and used as I ubsequently described.

lustrariomassumethatthe right answeris"A."lfthe student appliestheprobetoacorrectpositiononanswerA,whicl maybetheletteritselforaboaorsomeotherv'maalimagr area,theprobepictsoffacerrainpairofvoltsgeswhleh arr TheXpositionsignalfromamplifier36istheat-'edvialead fed into the comparator members 37 and 42 as descnbad 3 into a signal comparator member 31 while the Y-coordinatesignal isamplitiediaamplifierdbandfodvialeaddl to a second signal comparator-42.

The numeral 43 denotes a magnetic tape recorder 'above.Atthesametime,theeorrectsignalvoltagesX'aadY havebeenestablishedoathechsrgestoragecoadsaaersl andflandarelikewisebeingfediatothesame 'comparamwithmecorrcctanswersthevoltagesareths prugrsmmed signals on the media thereof. l'low sach pronmeandtheand''ctrctntrstnggesedwhschiatarnscabtlss appropriate signal to the image storage and video converter member which in turn racommences the presentation of the aestgroupofimagesoathefaceolthe cathoderaytube.

Again, for purposes ofdiscussion, amume that the student answers the question by applying the probe to answer "B" rather than the correct answer "A." At this point the voltage X and X andY and Y aredifferentoratleastonepairisdifferent and thus the and circuit will not be actuated by the incorrectanswerfihisleavesthesamepictureonthecathode raytube foracertainlength cftimeafterwhich bymeansofa simple timer, the correct answer is presented and the program proceeds. This is accomplished simply by using a timer initiated pulse placed on the magnetic tape by the instructor in the programming. A score can be kept of such "overtime" or no response replies by the student by a standard electromechanical counter.

Similarly, for purposes of discussion, rather than having questions written out on the face 12, assume that the pre-programmed information from the instructor audiby, from the related audio system 114, asks the student, for example, to correctly point out a certain object presented on the face plate on the cathode ray tube screen. For example, with young children or in teaching a foreign language, assume that the instructor asks that they "point out a tree." At this point the video scene is presenting a tree and many other items and the student to answer the question properly must put the probe on the picture of the tree. lh hen the probe is applied to the proper position on the plate, assuming that the answer is correct, again X- and Y-coordinate signals are picked off and fed into the coinparator members 37 and 42 and compared with the programmed voltages from the magnetic recorder. If the student has applied the probe to the right place on the plate 18 again the and" circuit is energized and the program moves on to the next phase.

My system may be programmed with a controlled amount of error or size of the acceptable spatial area to be considered correct." This may be desirable particularly when a relatively large object is to be pointed out on the plate 12. For example, if the student is requested to point out a tree, the tree involves a certain area and it should not be required that the student touch a very small point on the plate. This is accomplished by providing a controlled amount of "noise" in the X'- and Y'- signais from the tape recorder which in turn produce an area of correct answer space on plate 18. As before, under the control of signals derived from separate tracks or carriers on the tape in playback unit 43, two signals are emitted just prior to the shutdown of the tape drive which is intended to give the viewer time to respond to the query. These two signals AX and AY' are the acceptable errors in X and Y that will be considered conect. Voltages proportional to AX and AV are stored on condensers 63 and 64. These voltages are applied to oscillators 65 and 66 which, in accordance with standard designs provide output amplitudes of "noise" proportional to input voltages AX and AY'. This noise" is added to the X- and Y-signals applied to the comparators. It will now be seen that the comparators 37 and 42 will be actuated if X X AX and Y l" A)" respectively, which is the desired result. Appropriate carrier frequencies for the AX'- and AY-signals are put on the magnetic tape with amplitudes proportional to the desired allowable spatial errors in X and Y. This is accomplished merely by using a calibrated potentiometer to control the output amplitude of oscillators. The potenliometers are set by the instructor for each answer or response situation.

l wish to turn next to the programming aspects of the preaentsystent. Forthistbesameapparatusisusedasharboen previously described. To set the framework let us first assume that the image storage and converter member 50 has caused a pictorial scene to be presented on face plate 12 along with related audio. While at this point the instructor may merely record audio instruction, for purposes of illustration asnrme that such scene illustrates a question and four possible answers with related boxes, A, B, C and D. The correct answer I "A" andtheinstructorwishestoprogrsmthevoltagecoordinates ofBosAonthemediaofthetaperecorder41Themstrae1 thenappliesthetipofprobelitollosAongeaeratorU pick off the coordinate voltages as previously described. I mixedAC-DCsignalisfedvialeadatothesignalsepm'al 5 2!.Twosignal voltagesareestablishedinleads36band4ll now instead ofpassing into the comparators 37 and 42, loads 71 and 72, having appropriate switching, the split sign X'and l" arefed intothetape recorder forsubaequentr by the student. in the same programming sequence, the structor can set in the aforementioned AX'- and Al"-siga on appropriate tracks or carriers merely by dialing a pair suitably calibrated voltages into carrier oscillators whi produce signal amplitudes proportional to AX and Al" att time the probe 16 is activated by the instructor. When the structor removesthe probe from-contact with the sigr generator plate a signal termination signal is applied to tras of the tape recorder.

After a slight pause, following the recording of such X'- a 20 Y'-signals the programmer energizes a second circuit whi sends an appropriate impulse to the storage member 50, r .sentially a frame change signal, to cause the next frame frames to be displayed on the face plate 12. At the same til the recorder 43 is restarted and the programming via probe and leads 71 and 72 is continued, along with verbal comma tary as required fed in through microphone 436.

By this means the correct answer voltage coordinates a stored on the media of recorder 43.

When the student is using the apparatus and has been ash a question, as before, X- and Y-voltages are fed respective into comparator members 37 and 42. X'- and l"-signals a| AX'- and dr-signals are concurrently being fed into an comparators from the recorder 43 via leads 73 and 74, reaps tively. Ifthe answer is correct, impulses via leads 47 and 4' s tivate the image converter 50 causing frame change and t same electrical impulse via leads 47 and 4! inform t recorder 3 to move to the next series of X'- AX'- and Y AY-tspe In addition to being used as aforedescribed the preae system can be employed for live television polling activitir For this I use a standard home television receiver having I] signal generating apparatus, probe, plate and X- and Y-cor dinate splitting means, used in conjunction therewith. 11 video and audio signals are transmitted as is now done and r the flee plate 12 is presented a picture for which view response is requested. For example, "which of three ca didates, which of these four packages, etc., do you prefer The viewer applies the probe 16 to his response area and t! X- and Y-signals are generated as before. These are compan to X'- and Y'- (with AX and Al") signals supplied by tl audio carriers then enter the TV receiver along the norm audio of the program. The and" circuit is thus activated before, under the proper conditions and such signah may I stored by activating a punch card marker at the receiver f example, and then mailed to the collecting point or may I relayed instantly via phone litres or small dedicated rad transmitters back to a collection point. In the phone ii: polling system the "and" circuit can merely actuate a or phone dialer" which is standard equipment or the equivaler Ten different groups of lot) viewers each, for example, can I assigned different phone numbers and standard totalinrs busy signal counters at the exchanges can count the voter Using automatic dialers with a choice of four phone numbe permits expression by viewers of their choice among fo simultaneous options. To avoid overloading the telephor exchange equipment different small time delays of the on! ofsecondscanbebuiltintotheautomaticdialersindiflere homes. This is possible using standard techniques because ti dialersareofthemagneticrecordingtypeandmnalfldlffs ing)lengthsofailenttapeisallthatirequired.

ln thed'ucussionthusfarlhaveconsideradassachh systemarsdthelikewhereinifthestudentanswersaqueslil correctlytheprograrnproceedsontothe nestseriesofislru tiomandquestionsormthealternativeifthequestioa'ua swered wrong after a predetermined time the program tivelycoaneettoasecoad aad"circuitasambsr I27 prot'aeedalnowwishtoturntoceltainmodificationsofthe pulsesinsuchleadsactuatesuch"and"circuitmelnh presentaystemwhereinadd'aionalinformationortherlght lattermemberinmrnaetuatesasecondpre-record answerispreseatadtothestm'lentifaquesticnisanswered recorderluwhichfeedsintotheaudiospeakermen wrong. In conjuactionwiththisdiscussion refereneeshouldhe toadd explanatory information tothe student. Micro hadtoFlG.3. for the required time arch second recorder advanci Again, assumetllataquestion and4 possible answers, A, 8, next position-forthenext wrong answer explanation, C and D are projected onto the face plate 12. Voltage signaltoactivate recorder43andshutaotfforthetime dinates are The net result is that the student receives supplemt X Y AnswerA [0 formation which either gives him the right answer or hi X Y ,A B and ma close with for exam le n." x'y' :xc From tbe foregoing it wilL of be evident bl i AMI. similar supplemental and circuit members and taps ders, etc., are used in con'unetion with X Y and X tt'xiiz'timhw;znzizzifizrmlm i woman-mimm-dimi respectively. From amplifier 36, in parallel unconnected four I I Am" A 2s noxae must all be operated in the proper sequel n will be understood that various modifications and x' v' AnswerC V e trons may be efl'ected without departing from the sp 'n 'oscope of the novel concepts of my invention.

The tape recorder is connected into the comparators 9! I claim as my invention: through 98 in thesame manneras previously described in con- I A sum m a t with! m of m l W m 37 aion receivers comprising in combination:

a a source ofvideo ti rltlt which constitute the basic Lead 101 with capacitor 102 conveys signal X' through being m ""P l b. image reproduction means for displaying said Lead [04 conveys X. Mg; amplifier il c. manually movable probe means operable directly Lead 107 with c pacitor I08. conveys gienal X' gh said image reproduction means to electronically amplifier 109w comparator; and identify an X Y-coordinate in self-defining re Lead 110 with capacitor lli conveys signal X. through .tion with respecttosaidimagc; amplifier 112w comparator 91; d. means for pre-defining various fixed sets of X- an Lead 113 with capacitor 114 conveys signal Y, through coordinates constituting choices of positions relati amplifier 115 to comparator 95: a the same frame of reference as that of the basic imag Lead 116 with capacitor 117 conveys signal Y, through e. comparator means whereby sets of X'- and Y'-coord amplifier lldtocomparator 96; information previously defined are directly corn Lead 119 with capacitor 120 conveys signal Y, through with said probe means defined X- and Y coordi-iai amplifier lZl tocomparator 9'1;nnd formation such that said X- and Y-coordinates Lead "2 with capacitor 123 conveys signal Y, through identified with one specific set of X- and Y'-coordir| amplifier 124 to comparator 98. and

If the question posed to the student is answered correctl r ge means n ing a fixed. pre termined no the present system functions as described earlier. That is. as 56 additional infonnation such that the X and Y'-t sume that the correct answer is A and this is where the student to dentified control the output of said store: has applied the probe :6. Coinparatoii $4 and iii are ac'utatcd ditional Information means.

with x, being equal to x, and Y, being equal to Y,. Signals 1 The p "d in claim I e ei aid in from both comparators energize the "and" circuit member 46 m 1 i {'1 and the main program proceeds. 3. The system as defined in cla m I wherein the X'- and But assume now that the question is answered wrong, that in ll -"t freq ency. the correct answer i; "A" and h n d m mug v 4. Theaystemasdefined in claim I wherein the means W h probe h b g fi d m the 1 13 m pre-definmg Vll'tOtll fixed sets of coordinates include atl Xfl, are generated and fed into comparators 91 and 94 and m ""8 P 95 to 98. The counterpart signals from the recorder, X' Y, W!" 9 cllll'fl om at are being fed into'oomparators as and 96 only leaving the mdm P?" PP p q ys -m other comparators inoperative. Now, please refer to FIG. 4. wkm "I" W LeadslZSandlZfromeomparatorsflandfireqees a e o s 

1. A system useful as a teaching machine or polling television receivers comprising in combination: a. a source of video signals which constitute the basic image being transmitted; b. image reproduction means for displaying said basic image; c. manually movable probe means operable directly upon said image reproduction means to electronically define and identify an X - Y-coordinate in self-defining registration with respect to said image; d. means for pre-defining various fixed sets of X''- and Y'' coordinates constituting choices of positions relative to the same frame of reference as that of the basic image; e. comparator means whereby sets of X''- and Y'' -coordinate information previously defined are directly compared with said probe means defined X- and Y-coordinate information such that said X- and Y-coordinates are identified with one specific set of X''- and Y''-coordinates; and f. storage means containing a fixed, predetermined store of additional information such that the X''- and Y''-coordinates so identified control the output of said stored additional information means.
 2. The system as defined in claim 1 wherein said image reproduction means is a cathode ray tube.
 3. The system as defined in claim 1 wherein the X-, X''- and Y''-coordinates are recorded at sub-video frequency.
 4. The system as defined in claim 1 wherein the means for pre-defining various fixed sets of coordinates include at least one magnetic tape recorder.
 5. The system as defined in claim 1 wherein at least one coordinate pair is supplied with additive signals defining a tolerance region around exact spatial coincidence. 